Disappearing table



6, 1968 o. E. CUSSON 3,395,596

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DISAPPEARING TABLE Filed May 31. 1966 5 Sheets-Sheet 4 \AA H i TR R llll d Aug. 6, 1968 D. E. CUSSON DISAPPEARING TABLE 5 Sheets-Sheet 5 Filed May 31. 1966 INVENTOR. flamdl 62mm V ATTORNEYS United States Patent 3,395,596 DISAPPEARING TABLE David E. Cusson, Ambler, Pa., assignor to The Warner & Swasey Company, Cleveland, Ohio, a corporation of Filed May 31, 1966, Ser. No. 553,964 Claims. (Cl. 83-409) ABSTRACT OF THE DISCLOSURE The present invention relates to a disappearing table for supporting a workpiece for a machine tool and more specifically for a turret punch press having a centrally located screw advancing means that positions the work piece with respect to the punch.

A workpiece is generally secured against relative movement during punching by clamping means that grip the edge of the workpiece remote from the punch. The clamping means are suitably secured to a carriage assembly that can be manipulated with respect to the punch to position the workpiece at the desired location.

In the punching of sheet metal, it is necessary to support the workpiece over most of its surface at die height. This allows the sheet to lie flat and avoids distortion or other inaccuracies in the punched sheet. Conventionally a supporting table has been provided between the carriage and the punch which progressively recedes to avoid interference with the clamping means as the workpiece is advanced toward the punch. This assures continuous support of the workpiece in the space between the punch and the advancing carriage.

In machines of this type, the carriage is supported on guiding elements at either end and is advanced by dual advance means operably associated with both ends of the carriage. The supporting table consists of a plurality of pivotally interconnected elements riding on tracks parallel to the longitudinal direction of movement of the carriage. Suitable guiding elements aflixed to the carriage guide the leading edge of the table downwardly and below the carriage as the carriage advances toward the punch so as to move it progressively out of interference with the clamping means on the carriage, the table maintaining die height to a point just in advance of the forward end of the clamping means.

However, in order to permit the table to recede below die height and to pass under the advancing carriage, it has been necessary to motivate the carriage with advancing means operating along either side of the carriage. These conveniently are rack and pinion mechanisms or screw advancing means. Since a plurality of advancing means is being used, however, it is difiicult to synchronize them and inherent inaccuracies have developed in the final product due to the fact that the two ends of the carriage did not always advance or retract the same distance which causes the workpiece to move out of proper alignment.

Hence, it was necessary to provide a single advancing means for the carriage to eliminate these inaccuracies but in order to use a single advance means it was necessary to centrally located it with respect to the carriage. Preferably, this is a lead screw extending along the longitudinal direction of motion of the carriage that is operably associated with the center of the carriage, the carriage being supported at both ends along suitable ways or guides for slidable movement with respect to the punch. However,

3,395,596 Patented Aug. 6, 1968 in using a centrally located screw, it is impossible to get the table to recede below die height as the carriage advances toward the punch, since the screw will interfere with the receding movement of the table.

It is therefore an object of this invention to provide a means for supporting a workpiece substantially over its entire surface as it is manipulated with respect to a punch by an assembly that is advanced by a centrally located advancing means.

It is a further object of this invention to provide a sup porting means for a workpiece between the punch press and suitable clamping means affixed to a centrally advanced carriage for manipulating the workpiece with respect to the punch wherein the clamping means are also capable of moving transverse to the longitudinal direction of motion of the carriage.

It is a further object of this invention to provide a supporting table means that supports a workpiece between advancing workholders and the punch press, wherein the table means progressively recedes to avoid interference with workholders attached to the carriage While continuously supporting the workpiece as the carriage advances under action of a centrally located advancing means.

It is a further object of this invention to provide a disappearing table for a punch press that progressively recedes in advance of the carriage supporting the workholders wherein the table passes between the body of the carriage and the workholders.

It is a further object of this invention to provide a disappearing table for a punch press comprising a plurality of tubular roller bars pivotally interconnected to form a chain of roller bars for supporting a worlcpiece that progressively recedes below die height as the carriage assembly moves toward the punch wherein the chain of roller bars progressively accedes back to die height as the carriage assembly moves away from the punch.

It is a further object of this invention to provide a disappearing table for a turret punch press that is low in cost of production, that provides adequate support for the workpiece during the entire operation and that smoothly and quickly drops out of interference with an advancing carriage means driven by a centrally located advancing means.

These and other objects will become more apparent from the following descripitons of the drawings:

FIGURE 1 is a perspective view of the disappearing supporting table showing its location with respect to a punch on the right and the carriage and clamping assembly on the left.

FIGURE 2 is a top plan view of the punch press of FIGURE 1 in a retracted position.

FIGURE 3 is an end view of the punch press of FIG- URE 2.

FIGURE 4 is an enlarged right side sectional view taken along the lines 4-4 of FIGURE 3.

FIGURE 5 is an enlarged right side sectional view taken along the lines S5 of FIGURE 3.

FIGURE 6 is a fragmentary top plan view of the disappearing table.

FIGURE 7 is a fragmentary sectional view of the disappearing table with the workpiece in a retracted position.

FIGURE 8 is a fragmentary sectional view of the disappearing table similar to FIGURE 7 but with the workpiece partially advanced toward the punch.

FIGURE 9 is an enlarged sectional view taken along the lines 9-9 of FIGURE 7.

Referring to the drawings, and in particular to FIG- URES 1-5, there is shown a main table assembly 30 for the turret punch press having afiixed thereto ways or rods 31 upon which is mounted a carriage 32 for movement of a workpiece with respect to the punch and die area 33. Disposed between the punch and the carriage 32 is a disappearing table 34 consisting of a plurality of tubular rollers 35 forming a chain of roller bars rotatably mounted and pivotally interconnected by links 36. The rollers 35 are spaced apart in parallel relationship to provide a movable and continuous support for a workpiece at die height. Rotatably mounted to the ends of the rollers 35 are follower rollers 37 adapted to ride along stationary tracks 38 aifixed to the main table assembly and auxiliary tracks 39 movable with the carriage 32 the function of which will be described below.

The carriage 32 consists of a transverse beam 40 connected between side blocks 41 having side stringers 41' integrally connected therewith and extending along both sides of the disappearing table 34. Mounted to the stringers 41' for movement with the carriage are side tables 42 which are adapted to support a workpiece at die height beyond the range of movement of the workholders as they advance toward the punch. Extending downwardly from the blocks 41 are guide blocks 43 which mount the carriage for slidable movement along the rods 31.

The carriage supports a cross bar 44 at either end transverse to the longitudinal direction of motion of the carriage and is secured thereto by an adjustable means 45 within depressions 46 on the top surface of the side blocks 41 of the carriage. The cross bar has guide bars 50 upon which is mounted for slidable movement a cross slide 51.

Pneumatically operated workholders 52 are adjustably mounted to the cross slide in track 53 for adjustment relative to the cross slide depending on the size of the workpiece to be secured. The workholders grip the edge of a workpiece and consist of a stationary lower jaw 54 and upper jaw 55 pivotally mounted with respect to the lower jaw, the workholders including hydraulic means 56 which engage the jaws in gripping relationship with respect to the edge of a workpiece as shown for example in FIGURE 7.

In operation, the cross slide 51 is adjustable along the X axis in a direction transverse to the direction of motion of the carriage by a suitable screw advancing means 57 carried by the cross bar 44.

A longitudinally located lead screw 60 provides the control and motivation means for the movement of carriage 32 and the attached cross bar assembly along the Y axis in a longitudinal direction with respect to the punch area 33. Simultaneously with movement of the carriage along the Y axis, the cross slide and workholders can be adjusted along the X axis by movement of the cross slide in the cross bar as described above so as to properly locate the workpiece with respect to the punch, all movement being controlled by a suitable control means not shown.

The centrally located lead screw 60 is driven by a motor 61 that is operably associated through collar 62 attached to the transverse beam 40 with the carriage 32 for control and movement of the carriage and hence the workpiece along the Y axis. The use of the single lead screw limits the amount of inertia in the System and eliminates the inaccuracies inherent in a system utilizing a pair of advancing means. To avoid interference between the centrally located lead screw and the disappearing table, the transverse beam 40 of the carriage is suspended below the cross bar 44 so as to provide an opening 63 between the cross bar and the beam of the carriage through which the disappearing table 34 passes as will be described below.

Secured to the main table assembly beyond the limit of range of travel of the carriage are vertical posts which support the stationary tracks 38 at a level between the cross bar 44 and the carriage beam 40. The tracks 38 are stationary with respect to the carriage and extend parallel to the lead screw 60 and are suitably secured at their opposite ends to the main body of the punch at 71. Attached to the side tables 42, on either side of the disappearing table and disposed directly above and adjacent the main tracks 38 are auxiliary tracks 39 adapted to move with the carriage as it advances toward the punch. The relationship between the tracks can be seen by reference to FIGURE 9. An apron 72 attached to the side tables 42 and flush with the surface of the table fills the gap between the side tables and the ends of the rollers 35 forming the disappearing table 34.

The auxiliary tracks 39 have a wedged end 73 that lifts the follower rollers 37 of the roller bars 35 off of the stationary tracks 38 and on to the auxiliary tracks 39 as the carriage recedes from the punch area. The wedged end 73 of the auxiliary track is disposed slightly in front of the foremost end of the lower jaw 54 of the workholders 52 as shown for example in FIGURES 7 and 8. Since the rollers 35 are pivotally interconnected they will be progressively raised to die height at a point just in front of the workholders as the carriage recedes since the auxiliary tracks and the workholders move simultaneously with movement of the carriage. This provides continuous support for a workpiece within the space between the workholders 52 and the punch area 33.

As the workholders are advanced toward the punch area, the chain of rollers 35 forming the disappearing table 34 will successively drop off the auxiliary tracks 39 by rolling down the wedged end 73 of the auxiliary tracks 39 at a point just in front of the workholders in order to avoid interference between the workholders and the roller bars while maintaining support for a workpiece at die height in the space between the workholders and the punch. The chain of rollers forming the disappearing table is fastened to the main body of the punch at 75 and hence remains relatively stationary with respect to movement of the carriage.

In operation and with the carriage at the far end of its range of movement remote from the punch, the entire disappearing table 34 is now supported at die height by the auxiliary tracks 39 so that the maximum amount of supporting surface for the worksheet is now disposed between the workholders and the punch. It can be seen from FIGURE 7, that the last roller 76 of the chain of rollers forming the disappearing table 34 is just slightly in front of the lower jaw 54 of the workholders 52 so that a workpiece 77 will be fully supported within the area between the workholders 52 and the punch area 33 to the right. As the workpiece advances toward the punch along the Y axis in response to the activation of the lead screw 60, the auxiliary tracks 39 will move with the carriage and with respect to the disappearing table permitting one roller bar 35 after another to progressively drop down olf the wedged end 73 and on to the main tracks 38.

With reference to FIGURE 8, it can now be seen that part of the disappearing table is supporting the workpiece 77 at die height by the auxiliary tracks 39 and the remainder of the table is below die height and out of interference with the workholders on the main tracks 38. Whereas the follower rollers 37 roll with respect to the auxiliary tracks 39 as it is pulled out from or pushed underneath them depending on movement of the carriage, the rollers merely rest on the main track 38 at a receded level below die height.

Since the carriage moves with respect to the disappearing table 34, the chain of rollers will pass through the opening 63 between the cross bar 51 and the transverse carriage beam 40 of the carriage and will not interfere with the advancing workholders 52 or the centrally located lead screw 60 that moves the carriage and the workholders with respect to the punch. The drop of the carriage to a receded level below die height need not be large and need only be approximately inch as it only has to drop an amount sufiicient to permit the top surface of the rollers 35 to pass beneath the lower jaw 54 of the workholders 52.

Thus, it can be seen that by dropping the carriage down and providing an opening between the carriage and the cross bar, that I have been able to provide a disappearing table for a turret punch press utilizing a single advancing means for the carriage that continuously supports a workpiece in all positions during the punching operation.

In view of my invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention with out copying the product shown, and I therefore claim all such insofar as they fall within the reasonable spirit and scope of my invention.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. In a punch press, a main table assembly, a carriage slidably mounted with respect to the main table assembly, advancing means centrally located with respect to the carriage for moving the carriage in a longitudinal direction with respect to the punch, a cross bar mounted at opposite ends to the carriage leaving an opening between the carriage and the cross bar, a cross slide operable along the cross bar transverse to the longitudinal direction of motion of the carriage, workholders on the cross slide adapted to grip the edge of a workpiece and table means for supporting a workpiece between the workholders and the punch at the die height of the punch, stationary track means on the main table assembly extending through the opening between the carriage and the cross bar for supporting the table means at receded level, auxiliary track means for supporting the table at die height, and means for transferring support of the table between tracks as the carriage moves with respect to the punch, wherein said table means progressively recedes below die height and passes through the opening between the carriage and the cross bar as the carriage advances toward the punch so as to avoid interference with the workholders.

2. A punch press of claim 1, wherein the table means comprises a plurality of pivotally interconnected roller elements :having followers operable along and between the said track means.

3. A punch press of claim 2, wherein the auxiliary track means are movable with the carriage and are disposed adjacent and above the stationary track means, said auxiliary track means having a wedged end positioned slightly in front of the workholders to transfer the followers of the roller elements between tracks as the carriage moves with respect to the punch.

4. A punch press of claim 2, wherein the pivotally interconnected roller elements are tubular bars rotatably mounted in parallel spaced relationship transverse to the longitudinal direction of motion of the carriage with pivotable interconnecting links.

5. A punch press of claim 1, wherein the advancing means comprises a lead screw.

References Cited UNITED STATES PATENTS 833,811 10/1906 Vold 83-71 X 1,342,878 6/ 192.0 Thom-as 83409 ANDREW R. JUHASZ, Primary Examiner. 

